Sync: Propagate block announcement data (#7903)

* Sync: Propagate block announcement data

This pr adds a feature to the sync protocol to propagate the data that
we received alongside a block announcement. This is done by adding a
cache that caches the last X block announcement data where X is set to
the number of `in_peers` (giving every peer the chance to send us a
different block). This will be required by parachains to ensure that
even peers who are not connected to a collator receive the data
alongside the block announcement to properly validate it and request the
block.

* Review comment

* Bring back the code and add new variant to ensure we don't insert block
announce data when something wasn't checked

* Also use out_peers

substrate/client/network/Cargo.toml

@@ -35,6 +35,7 @@ hex = "0.4.0"
 ip_network = "0.3.4"
 linked-hash-map = "0.5.2"
 linked_hash_set = "0.1.3"
+lru = "0.6.3"
 log = "0.4.8"
 nohash-hasher = "0.2.0"
 parking_lot = "0.11.1"